JPS6054275A - Method for controlling driving of welding torch - Google Patents

Abstract

PURPOSE:To perform exactly operation for correcting profiling of a weld line in the direction normal to said line by detecting the direction of the weld line during welding in accordance with teaching data and correcting data for profiling and correcting the moving direction of a welding torch by profiling control so as to bring the same in the direction normal to the direction of the detected weld line. CONSTITUTION:A mechanism for controlling driving of a welding torch 1 provided with a wrist part 2 having an S-axis to oscillate the torch 1 and a B-axis to bend the torch 1 and an arm part 3 having plural axes to control the position of the part 2 is operated in the following way: the directions X, Y, Z of the weld line presently under welding are detected by the teaching data for controlling the driving of the respective axes S, B to move the top end of the torch 1 along the weld line and the correction data for profiling by the detected deviation are preliminarily detected. The axes S, B of the arm part 3 are simultaneously controlled in such a way that the moving direction along the actual weld line of the torch 1 is brought to the normal X', Y', Z' of the weld line in accordance with the direction of the detected weld line mentioned above. In the figure, 4 denotes a control device for a welding robot and 5 a teaching box, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the drive of a welding torch in a welding robot.

As this type of welding robot, there are five types of welding robots, as shown in FIG. This welding robot has a welding torch l
The welding torch 1 is equipped with two rotating axes that control the attitude of the welding torch 1, that is, an S axis that swings the welding torch 1 left and right and a B axis that bends the welding torch 1 up and down (Fig. 2 (a) and (b)).
(see), and a horizontal (Y)
A robot body consisting of an arm 3 in a vertical (→) orthogonal coordinate system, a welding robot control device 4, a teaching box 5,
It consists of a welding power supply device 6 and a welding wire box 7.

When controlling the welding torch using the teaching 1 playback method in such a welding robot, first the X, Y of the welding torch 1 is controlled by the teaching box 5.
, instruct movement in the Z-axis direction, move the tip of the welding torch l to the desired teaching point, and set the position of the X, Y, and Z axes at this point and the angles θB and θB of the S and B axes to the bath welding robot. Transfer the teaching data to the memory of the controller head 4.
After completing the fourth writing and teaching, when moving the welding torch tip along the welding line taught by the teaching data, find the position data of the two teaching points from the position data of each axis (teaching data), Calculate the distance between these two points, divide it equally to determine the number of interpolation points, and then perform interpolation calculations. As a result,
1. Interpolation can be obtained by tracing a straight line (or circle) between two points. On the other hand, reverse coordinate transformation is performed to obtain the position data of each axis, and each axis is controlled based on this position data example.In addition, when welding, the actual weld line is detected by a weld line detection means such as an arc sensor, The output of the welding line detection means further controls each of the axes so that the welding torch follows the actual welding line.

By the way, conventionally, when controlling the welding torch by following the output of the welding line detecting means, the tip of the welding torch is set as the coordinate origin, and the tangential direction of the arc drawn by the tip of the welding torch when rotating the B axis is x / (th 2 (a)), the tangential direction of the arc drawn by the tip of the welding torch when rotating the B axis is Y', and the extension direction of the welding torch ya:z'c in Figure 2 (b
Using the torch coordinate thread defined as (see ), the negative deviation from the weld line detected above was converted into the torch coordinate system for tracing control.

Therefore, if the welding torch 1 - is deviated from the welding line as shown in Fig. 3, move the bath welding torch in the direction of the Y' force so that the welding torch is on the dashed-dotted line (on the welding line). :
It is controlled by imitating sea urchins.

As shown in Fig. 4, in such tracing control, if there is no advancing angle or receding angle, or if the sinking angle is small, there is no problem even if there is a slight deviation between the taught welding line and the actual welding line. (See Figure 5) As shown in Figure 6, if the taught welding line (dotted line) and the actual welding line are misaligned, and the welding torch has an advancing angle or a receding angle, the arrow will appear at the corner of the welding line. Overshoot may occur as shown in A, and the quality of the m-contact is significantly degraded here. seven,
When the f6 tangent is performed in the direction of arrow B, the angle α is the advancing angle, and when the f6 tangent is performed in the direction of arrow 1, the angle α is the receding angle. In addition, in order to avoid interference between the welding torch and the workpiece at the corners of the welding line, the welding torch should not be held in the position shown in Figure 1 and Figure 5, but the advancing and receding angles should be adjusted as shown in Figure 6 (Figure 6). It is normal to set this up and deal with it.

Therefore, conventional tracing control has problems such as being limited by overshoot, advancing angle, and receding angle of the welding torch.

The second invention aims to provide a welding torch drive control method that can solve the above problems.

According to this invention, the direction of the welding line currently being welded is detected based on teaching data and scanning correction data, and the moving direction of the welding torch by scanning control is set to the normal direction of the detected welding line. We are trying to resolve the above problems.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 7 is a block diagram showing an example of the configuration of a control device for implementing the welding torch control method according to the present invention. now,
As shown in FIG. 8, a case where the teaching wire pieces and the actual welding line iIi are misaligned will be described.

The first mesori lO has each teaching point p, , p in advance.

The teaching data (xrY*zHQ''tθ) of each axis of the arm 3 and wrist 2 of the robot in is stored.

The central processing unit C0PU) 11 extracts position data of teaching points P1 and P2 from the teaching data.
(XH+7t +z+) +Pt (zntyt,
zl)', calculate the distance between these two points, divide it equally, determine the number of interpolation points, and then perform interpolation calculation. As a result, the position data for each minute distance zl between points C and P are as shown in Table 1.

Table 1 The position data in Table 1 is the first memo! JIOK will be remembered.

The CPU II sequentially inputs the position data in Table 1 above,
A movement command value for each axis is calculated and added to the subtracter 12. To the other input of the subtractor 12, a number of pulse signals corresponding to the moving distance of the shaft, that is, the amount of rotation of the shaft drive motor 140, is applied from the encoder 13, and the subtractor 12 is configured to receive a deviation between the two human power signals. and leads it to the position deviation counter 15 (The count value of the position deviation counter 150 is D
/A converter 16 converts it into an analog signal and subtracter 17
added to. The other input of the subtractor 20 is the speed detector 1.
An analog signal corresponding to the rotational speed of the shaft drive motor 40 is added from 8, and the subtracter 17 takes the deviation of the two human power signals and leads it to the shaft drive motor 4 via the servo amplifier 19.

In addition, the arc current value 14 detects the actual welding line based on the arc current value at both ends of the weaving during weaving overlap, and outputs correction data 1-5 so that the welding torch tip follows the actual welding line. .

0PUI 1 outputs movement command values for each axis based on the above correction data, performs a tracing control N-f on the tip of the welding torch, which will be described later, and compares the taught welding line with the actual welding line as shown in Figure 8. The amount of deviation (ΔYi) is stored in the second memory 21 for each position where the welding line is equally divided by the distance Δl. Note that if the sensor correction amount for each Δl is Eχ, then the amount of deviation between the taught welding line and the actual welding line (ΔYi
) is ΔYi−aΣ Kχ ・・・・・・ (1) χ=
It can be expressed as 1. That is, the scanning correction data in the second memory 21 when welding the position Q is as shown in Table 2.

Table 2 Therefore, the position data of the actual welding line can be determined from the contents of the first memory IO and the second memory 21. Therefore, the inclination of the actual welding line with respect to the X-axis when welding at position Q is I will explain how to set Q. Now, as shown in FIG. 9, the newest predetermined number (four in this case) of scanning correction data (ΔY
, ΔYQ-, , ΔYCL-, , ΔYQ), and these phases S S-ΔYQ-Fuju ΔYQ-! +ΔYQ-1+ΔYQ・・
...Calculate (2) by it. If ΔYQ-3, ΔY
Q-2. ΔYQ-1. If ΔY( are all on the straight line of angle θ, then the linear formula % formula % holds true. Therefore, taking the phases of the left and right sides of equation (3), Δ′1q−1+ΔYQ−1+ΔY Q −1+ΔYQ .

-+1+2+3-1-4)Δl-θ-10×ΔI! −〇 ・・・・・・(4). The above formula (2) and the formula (4)
) Subtracting the angle θ from the equation gives 1 uxbt. In addition, in reality, ΔYcl-8. ΔYQ-1.
Although ΔYQ and Δyt4 include errors due to variations, the value of angle 0 calculated by the above equation (5) is
These variations are leveled out. In addition, in this example, for the sake of simplicity, the case where the taught welding line coincides with the Using the tracing correction data, the inclination of the m tangent currently being welded can be adjusted in the same manner as described above.

Based on the slope θ of the m tangent detected in this way)
As shown in FIGS. 1O (a) and (b), the welding torch can be moved in the normal direction θχ of the actual welding line. Here, θχ is θχ=90″10 (','o≦θ〈90°)θ −9
It can be expressed as 0° (', "90≦θ<180").

0PUl l calculates the base axis movement command value in step 5 so that the direction of tracing control of the welding torch tip based on the correction data from the arc sensor 2o is the normal direction of the welding line drawn as described above. Output.

In this embodiment, the arm has three orthogonal axes, X, Y, and Z, but the arm may have other axial configurations as long as it moves the position of the wrist.

As explained above, according to the present invention, the correction operation is performed by accurately following the normal direction to the welding line regardless of the orientation of the welding torch. In addition, the posture of the welding torch is no longer restricted, and the range of joints that can be welded can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an m-welding robot to which the present invention is applied, FIGS. 2(a) and 2(b) are a plan view and a side view of the wrist of the welding robot, respectively, and FIGS. FIG. 6 is a diagram showing the relative positions of the welding torch and workpiece used to explain the defects in the conventional scanning correction operation, and FIG. 7 is a control device for implementing the welding torch drive control method according to the present invention. 8 is a block diagram showing a configuration example of , and FIG. 8 is a diagram showing the relationship between the taught m tangent and the actual welding line.
Fig. 9 is a diagram used to explain an example of adjusting the inclination of the welding line, and Fig. 1θ @) and Fig. 1O (b,) respectively explain the alignment direction when correcting the welding torch by copying it. This is a diagram used for this purpose. l...Welding torch, 2...Wrist part, 3...Arm part, 4...Bath contact robot control device, 5...Teaching box, lO...First memo'J , 11... central processing unit (CPU) 20... arc sensor, 21...
-Second memory. Figure 8

Claims (1)

[Claims] Swing the welding torch S axis and welding 1 - bend B @
and an arm having a number of axes for controlling the position of the handcuffs, and drives each of the axes so that the tip of the welding torch follows a welding line taught in advance by teaching data. While controlling, weaving welding r
c Welding 1. - In the welding torch drive control method, the welding torch is controlled to follow the actual welding line by detecting a deviation between the welding tip and the actual welding line based on the detected deviation, and the teaching The direction of the welding line currently being welded is detected based on the data and copying correction data based on the detected deviation, and the moving direction of the welding torch in the copying control is determined based on the detected direction of the welding line. A method for controlling the drive of a welding torch, the feature of which is to simultaneously control each axis of the arm so that the axis is in the linear direction.